The particle size, and exhibit optical, electric, and magnetic characteristics of nano particles are completely different from those of a bulk-state material due to a quantum confinement effect in which the energy required for electron transfer is changed depending on the size of material, and a large specific surface area. Thus, due to these properties, much interest has been focused on the applicability in the fields of catalysts, electro-magnetics, optics, medicine, and the like. Nano particles may be an intermediate between bulk and molecule, and in terms of an approach in two ways, that is, a “Top-down” approach and a “Bottom-up” approach, it is possible to synthesize nano particles.
Examples of a method for synthesizing metal nano particles include a method for reducing metal ions with a reducing agent in a solution, a method using gamma rays, an electrochemical method, and the like. However, methods in the related art are problematic in that it is difficult to synthesize nano particles having a uniform size and shape, or the use of an organic solvent leads to environmental pollution, high costs, and the like. For these various reasons, it was difficult to economically mass-produce nano particles. Therefore, there is a need to develop high-quality nano particles having a uniform size.